In Overfall, your party can gain passive abilities called "Personas" when certain conditions are met. They can be either harmful or beneficial. Some effects are temporary while others are permanent. There are are no levels in Overfall, so gaining beneficial Personas, along with skill and weapon upgrades are key to gaining power.

Well I still like the "level up" and XP system. I wouldn't want to give that up completely I also don't like much auto-leveling enemies, because it makes the whole thing feel much more like a game than a story/world, it breaks immersion: